<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      .box {
        width: 200px;
        height: 200px;
        border: 1px solid #000;
      }
      .red {
        background-color: #f00;
      }
      .bigBd {
        border: 10px solid #000;
      }
    </style>
  </head>
  <body>
    <div id="app">
      <button @click="isRed=!isRed">切换颜色</button>
      <button @click="isBig = !isBig">切换边框</button>
      <div class="box" :class="{red:isRed, bigBd:isBig}"></div>
    </div>
    <script src="./vue.js"></script>
    <script>
      new Vue({
        el: "#app",
        data: {
          isRed: true,
          isBig: true,
        },
      });
    </script>
  </body>
</html>
